In some examples, an embodiment of the present invention relates generally to a solid catholyte or electrolyte material having desired ion conductivity. More particularly, an embodiment of the present invention provides a method and structure for a catholyte material to improve a total ionic conductivity for a cathode to allow for higher mass loading of an active material, faster charge/discharge, and a wider range of operating temperature. Merely by way of example, the invention has been applied to solid state battery cells, although there can be other applications.
A high level of development has caused an explosion in electronic and communication apparatus. As an example, such apparatus include, among others, a personal computer, a video camera and a portable telephone, commonly termed a “smart phone.” Examples of popular smart phones include the iPhone™ from Apple Inc. of Cupertino, Calif. or those phones using the Android™ operating system of Google Inc. in Mountain View, Calif. Other popular apparatus include electric or hybrid automobiles such as those from Tesla Motors Inc. in Fremont, Calif. or the Prius manufactured by Toyota Motor Corporation. Although highly successful, these popular apparatus are limited by storage capacity and in particular battery capacity. That is, a higher power and higher capacity battery for an electric automobile or a hybrid automobile would be an advance in the automobile industry. A lithium battery has been presently noticed from the viewpoint of a high energy density among various kinds of batteries.
Liquid electrolyte containing a flammable organic solvent has been used for conventional lithium batteries. Liquid electrolytes suffer from outgassing at high voltage and pose a threat of thermal runaway due to the enthalpy of combustion of the solvents. A lithium battery configured with a solid electrolyte layer (replacing the liquid electrolyte) has been described to improve the safety of the battery. A sulfide solid electrolyte material has been known as a solid electrolyte material used for a solid-state lithium battery. As an example, a solid electrolyte material is described in EP2555307 A1 published Feb. 6, 2013, and filed Mar. 25, 2011, which claims priority to Mar. 26, 2010, in the names of Ryoji Kanno and Masaaki Hirayama, assigned to Tokyo Institute of Technology and Toyota Jidosha Kabushiki Kaisha, which is hereby incorporated by reference.
State of the art solid state batteries are not ready for mass market adoption due to limited power density, mass loading, and manufacturability. Accordingly, techniques for improving a solid-state battery are highly desired.